Without pictures I am unable to render an educated guess. If they are still uneven after 3 months, you have a few options. One is to live with it. Easiest way to adjust volume is with liposuction. I have done touch up lipo on breasts in the office with rib blocks and local with excellent results. If the asymmetry is extreme re-operation may be needed. Hopefully after the swelling has abatted you won't need any intervention at all. Be patient.
Without photos, I can not really comment, but initial post-op results will change as the swelling subsides in each breast.
One breast considerable larger after reduction! Any suggestions?
I am sorry to hear about your concerns after breast reduction surgery. "Considerably larger" asymmetry would concern me that there is a potential problem going on; it will be best to communicate these concerns directly with your plastic surgeon. Sometimes, asymmetric swelling around the time of surgery may be a sign of a complication. Again, your plastic surgeon will be your best resource when it comes to accurate assessment, advice, or meaningful reassurance.